Environmental Status of Cryptococcus neoformans and Cryptococcus gattii in Colombia

SAGA Complex Subunit Hfi1 Is Important in the Stress Response and Pathogenesis of Cryptococcus neoformans

The Spt-Ada-Gcn Acetyltransferase (SAGA) complex is a highly conserved co-activator found across eukaryotes. It is composed of a number of modules which can vary between species, but all contain the core module. Hfi1 (known as TADA1 in Homo sapiens) is one of the proteins that forms the core module, and has been shown to play an important role in maintaining complex structural integrity in both brewer's yeast and humans. In this study we successfully identified the gene encoding this protein in the important fungal pathogen, Cryptococcus neoformans, and named it HFI1. The hfi1Δ mutant is highly pleiotropic in vitro, influencing phenotypes, ranging from temperature sensitivity and melanin production to caffeine resistance and titan cell morphogenesis. In the absence of Hfi1, the transcription of several other SAGA genes is impacted, as is the acetylation and deubiquination of several histone residues. Importantly, loss of the gene significantly impacts virulence in a murine inhalation model of cryptococcosis. In summary, we have established that Hfi1 modulates multiple pathways that directly affect virulence and survival in C. neoformans, and provided deeper insight into the importance of the non-enzymatic components of the SAGA complex.

First report of environmental isolation of Cryptococcus and Cryptococcus-like yeasts from Boyacá, Colombia

The Cryptococcus genus comprises more than 100 species, of which C. neoformans and C. gattii are the leading cause of cryptococcosis. The distribution of C. gattii and C. neoformans species complexes has been extensively studied and widely reported globally. Other species such as Naganishia albida, Papiliotrema laurentii, and Papiliotrema flavescens have been reported as pathogenic yeasts. Since there are no reports of environmental isolation in the Boyacá region (Colombia), this study aimed to isolate and characterize Cryptococcus and Cryptococcus-like yeasts from pigeon feces, Eucalyptus, and olive trees distributed in the municipalities of Tunja and Ricaute Alto. The environmental data was recovered, and the isolations obtained were identified by microscopy, biochemical test, MALDI-TOF MS, URA5-RFLP, and sequencing of the ITS and LSU loci. For the 93 pigeon dropping samples collected in Tunja, 23 yielded to C. neoformans, 3 to N. globosa, 2 N. albida and 1 to P. laurentii. Of the 1188 samples collected from olive trees, 17 (1.43%) positive samples were identified as C. gattii species complex (4), C. neoformans species complex (2), P. laurentii (3), N. albida (2), N. globosa (5) and P. flavescens (1). Likewise, specimens of C. neoformans presented molecular type VNI and molecular type VNII; for C. gattii the molecular types found were VGIII and one VGIV by URA5-RFLP but VGIII by MALDI-TOF and sequencing of the ITS and LSU. Therefore, it can be concluded that the species of Cryptococcus, Naganishia and Papiliotrema genera, are present in the environment of Boyacá, and show a predilection for climate conditions that are typical of this region.

Predictive Performance of Scoring Systems for Mortality Risk in Patients with Cryptococcemia: An Observational Study

Cryptococcal infection is usually diagnosed in immunocompromised individuals and those with meningeal involvement, accounting for most cryptococcosis. Cryptococcemia indicates a poor prognosis and prolongs the course of treatment. We use the scoring systems to predict the mortality risk of cryptococcal fungemia. This was a single hospital-based retrospective study on patients diagnosed with cryptococcal fungemia confirmed by at least one blood culture collected from the emergency department covering January 2012 and December 2020 from electronic medical records in the Taichung Veterans General Hospital. We enrolled 42 patients, including 28 (66.7%) males and 14 (33.3%) females with a mean age of 63.0 ± 19.7 years. The hospital stay ranged from 1 to 170 days (a mean stay of 44.4 days), and the overall mortality rate was 64.3% (27/42). In univariate analysis, the AUC of ROC for MEWS, RAPS, qSOFA, MEWS plus GCS, REMS, NEWS, and MEDS showed 0.833, 0.842, 0.848, 0.846, 0.846, 0.878, and 0.905. In the multivariate Cox regression analysis, all scoring systems, older age, lactate, MAP, and DBP, indicated significant differences between survivor and non-survivor groups. Our results show that all scoring systems could apply in predicting the outcome of patients with cryptococcal fungemia, and the MEDS displays the best performance. We recommend a further large-scale prospective study for patients with cryptococcal fungemia.

Exposure of Cryptococcus neoformans to Seven Commonly Used Agricultural Azole Fungicides Induces Resistance to Fluconazole as Well as Cross-Resistance to Voriconazole, Posaconazole, Itraconazole and Isavuconazole

BACKGROUND

Cross-resistance to medical azoles by exposure to azole pesticides is well documented for Aspergillus family fungi but is poorly evaluated for other environmental pathogen fungi, particularly for yeasts belonging to the Cryptococcus neoformans/Cryptococcus gattii species complexes.

METHODS

One thousand C. neoformans yeast were exposed to various concentrations of seven different commonly used azole pesticides. Clones surviving exposure were picked randomly, and their minimal inhibitory concentrations (MICs) of fluconazole, voriconazole, posaconazole, itraconazole and isavuconazole were assessed.

RESULTS

Depending on the pesticide used for exposure, up to 13.3% of selected Cryptococcus colonies showed a phenotype of resistance to fluconazole, and among them, several showed cross-resistance to another or several other medical azoles. Molecular mechanisms involved in the resistance setups seem to be dependent on ERG11 and AFR1 gene overexpression.

CONCLUSION

Exposure to any of the seven azole pesticides tested is capable of increasing the MIC of fluconazole in C. neoformans, including up to the level of the fluconazole-resistant phenotype, as well as generating cross-resistance to other medical azoles in some cases.

A Landscape of the Genomic Structure of Cryptococcus neoformans in Colombian Isolates

Cryptococcus neoformans species complexes are recognized as environmental fungi responsible for lethal meningoencephalitis in immunocompromised individuals. Despite the vast knowledge about the epidemiology and genetic diversity of this fungus in different regions of the world, more studies are necessary to comprehend the genomic profiles across South America, including Colombia, considered to be the second country with the highest number of Cryptococcosis. Here, we sequenced and analyzed the genomic architecture of 29 Colombian C. neoformans isolates and evaluated the phylogenetic relationship of these strains with publicly available C. neoformans genomes. The phylogenomic analysis showed that 97% of the isolates belonged to the VNI molecular type and the presence of sub-lineages and sub-clades. We evidenced a karyotype without changes, a low number of genes with copy number variations, and a moderate number of single-nucleotide polymorphisms (SNPs). Additionally, a difference in the number of SNPs between the sub-lineages/sub-clades was observed; some were involved in crucial fungi biological processes. Our study demonstrated the intraspecific divergence of C. neoformans in Colombia. These findings provide evidence that Colombian C. neoformans isolates do not probably require significant structural changes as adaptation mechanisms to the host. To the best of our knowledge, this is the first study to report the whole genome sequence of Colombian C. neoformans isolates.

Gene expression profiles of ERG11, MDR1 and AFR1 in Cryptococcus neoformans var.grubbi from HIV patients

Introduction: Fluconazole is the most used antifungal drug for prevention and treatment of Cryptococcus spp. infections, the etiological agent of cryptococcosis. Resistance to fluconazole among Cryptococcus neoformans isolates can lead to treatment failure and generate relapses. Objective: To evaluate the expression profiles of the AFR1, MDR1 and ERG11 genes in C. neoformans var. grubii clinical isolates during the in vitro response to fluconazole induction. Materials and methods: Fourteen C. neoformans var. grubii isolates recovered from HIV patients were studied, in which 6 showed sensitivities to fluconazole and 8 decreased sensitivity. The expression levels of ERG11, AFR1 and MDR1 genes were determined by real-time PCR from extracted mRNA. Results: AFR1 and MDR1 genes from C. neoformans var. grubii were overexpressed in fluconazole resistant isolates, whereas ERG11 maintains homogeneous expression in all the evaluated resistance phenotypes of C. neoformans var. grubii isolates. Conclusions: The overexpression of AFR1 and MDR1 genes, which codify for efflux pumps, contributes to fluconazole resistance in the studied isolates. However, the resistance patterns in this fungus and the relapse cases in HIV patients cannot be attributed solely to the exposure to the drug. Heteroresistance and the emerging resistance (resistance through other ERG genes), might be other mechanisms involved in this phenomenon, which must be studied in these isolations.

Disseminated cryptococcosis mimicking malignant lymphoma on 18F-FDG PET/CT: A case report

RATIONALE

Disseminated cryptococcosis is extremely rare and is easily misdiagnosed as a malignant lymphoma. 18F-Fluorodeoxyglucose Positron Emission Tomography (PET)/ computed tomography (CT) may be useful to assess the involvement of disseminated cryptococcosis and to evaluate residual disease after treatment.

PATIENT CONCERNS

A 21-years-old man presented with fever and cough for a month, with multiple red nodules scattered on the skin. 18F- Fluorodeoxyglucose PET/CT revealed multiple hypermetabolic lymph nodes in the upper and lower parts of the diaphragmatic region and hypermetabolic nodules in the skin. According to the PET/CT results, malignant lymphoma was considered a possibility, especially T-cell lymphoma involving the skin.

DIAGNOSIS

Cryptococcosis was diagnosed using inguinal lymph node biopsy and blood culture.

INTERVENTIONS

The patient received two months of amphotericin B, fluconazole, and half a month of meropenem.

OUTCOMES

The patient's body temperature returned to normal and the red nodules on the skin disappeared. Most of the hypermetabolic enlarged lymph nodes disappeared, which was confirmed by reexamination with PET/CT.

LESSONS

Disseminated cryptococcosis is easily misdiagnosed as malignant lymphoma, especially when the lymph nodes are more involved. When multiple hypermetabolic enlarged lymph nodes appear on PET/CT, except for lymphoma, specific infections should also be considered.